Delivery unit

ABSTRACT

The invention relates to a delivery unit for delivering fuel in a motor vehicle. The invention is characterized in that a plastic casing ( 11 ) of a rotor ( 10 ) of an electric motor ( 1 ) is configured as one piece with a bush ( 13 ). A housing part ( 5 ) of a delivery pump ( 2 ) comprises a bearing shell ( 14 ) for said bush ( 13 ). This permits the delivery unit to be produced and mounted in a particularly cost-effective manner.

BACKGROUND OF THE INVENTION

The invention relates to a delivery unit, in particular for deliveringfuel, having a delivery pump which is driven by an electric motor,having an impeller wheel of the delivery pump, mounted between housingparts and is connected fixed in terms of rotation to a shaft which isdriven by the electric motor, and having a support arrangement for theshaft in a housing part.

Such delivery units are frequently used in contemporary motor vehiclesand are known from practice. In a known delivery unit, the shaft of theelectric motor has a radial support arrangement in one of the housingparts of the delivery pump. A carbon bush is pressed into the housingpart in order to provide radial support. The carbon bush has a borecorresponding to the shaft.

A disadvantage with the known delivery unit is that the bush can bedamaged during mounting as a result of tilting of the bush orexcessively large pressing-in forces. As a result, the delivery unit hasa short service life. Furthermore, the carbon bush gives rise to veryhigh mounting costs and material costs of the delivery unit.

The invention is based on the problem of configuring a delivery unit ofthe type mentioned at the beginning in such a way that it can bemanufactured particularly cost-effectively and has a particularly longservice life.

BRIEF DESCRIPTION OF THE INVENTION

This problem is solved according to the invention by virtue of the factthat a plastic casing of a rotor of the electric motor is fabricated inone piece with a bush which is arranged in the housing part, and thatthe housing part has a support shell for the bush.

As a result of this configuration, the radial support is produceddirectly by the housing part and the plastic casing which extends intothe housing part. Thanks to the invention, there is no need for a carbonbush for the radial support. Since the plastic casing is present in anycase in electric motors for contemporary delivery units, the deliveryunit according to the invention requires a particularly small number ofcomponents. The delivery unit according to the invention can thereforebe fabricated in a particularly cost-effective way.

With the known delivery unit, the shaft could have a flattened portionfor entraining the impeller wheel fixed in terms of rotation. However, afurther contribution to reducing the fabrication costs of the deliveryunit according to the invention is made if the bush has a coupling forconnection to the impeller wheel so as to be fixed in terms of rotation.As a result of this configuration, the shaft may be of cylindricalconfiguration in the region of the delivery pump. As a result of thisconfiguration, the shaft does not transmit any torque since the torqueis transmitted directly into the impeller wheel of the delivery pump bythe plastic casing of the rotor of the electric motor. For this reason,no torsional forces are applied to the shaft so that it can befabricated with a particularly small diameter, and thus a low weight.

According to another advantageous development of the invention, thecoupling has a particularly simple structural design if the coupling ofthe bush has a lateral flattened portion for connection to the impellerwheel so as to be fixed in terms of rotation.

A lateral flattened portion of the bush frequently requires a very largeinstallation space in the center of the impeller wheel. According toanother advantageous development of the invention, the delivery pump canbe made particularly compact if the coupling is designed to generate apositive lock between the axial faces of the bush and those of theimpeller wheel.

A contribution to simplifying the structural design of the delivery unitaccording to the invention further is made if the axial faces of thebush and those of the impeller wheel have projections and recesses whichcorrespond to one another. In addition, this permits the impeller wheelto be mounted in a position in the correct fashion in the delivery pump.

The bush could, for example, replace the shaft in the region of thedelivery pump. The delivery unit according to the invention has,however, a high degree of stability if the bush is arranged on theshaft.

Rotors for electric motors of contemporary delivery units frequentlyhave at least two plastic casings. According to another advantageousdevelopment of the invention, with such electric motors it is easilypossible to ensure that the bush is reliably supported by the shaft ifthe bush is fabricated in one piece with an internal plastic casing, anda plurality of external plastic casings, of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits numerous embodiments. In order to clarify itsbasic principle further, one of these embodiments is illustrated in thedrawing and will be described below. Said drawing shows a longitudinalsection through a delivery unit according to the invention in a singleFIGURE.

The delivery unit has a delivery pump 2 which is driven by an electricmotor 1. The delivery pump 2 is embodied as a side duct pump and is usedto deliver fuel in a motor vehicle. The fuel is delivered by thedelivery pump 2 in an axial fashion through an inlet duct 4 which isarranged in a housing part 3 to an outlet duct 6 which is arranged in afurther housing part 5. An impeller wheel 7 of the delivery pump 2 ismounted axially between the housing parts 3, 5 and is connected fixed interms of rotation to a shaft 8 of the electric motor 1. The electricmotor 1 has a fixed stator 9 and a rotor 10 with the shaft 8. The rotor10 has an internal plastic casing 11 and an external plastic casing 12.The inner plastic casing 11 is fabricated in one piece with a bush 13which is arranged in one of the housing parts 5 of the delivery pump 2.The housing part 5 has a support shell 14 for the bush 13. As a result,the shaft 8 is mounted radially in the housing part 5. In the otherhousing part 3 of the delivery pump 2, a ball 15 is arranged as an axialbearing for the shaft 8. In order to connect the impeller wheel 7 of thedelivery pump 2 to the rotor 10 of the electric motor 1 so as to befixed in terms of rotation, a coupling 16 with projections 17 andrecesses 18 which correspond to one another and which change over thecircumference are arranged on the adjoining end sides of the bush 13 andof the impeller wheel 7. The projections 17 and recesses 18 engage onein the other and connect the impeller wheel 7 to the bush 13 in apositively locking fashion.

1. A fuel delivery unit having a delivery pump which is driven by anelectric motor, having an impeller wheel of the delivery pump, which ismounted between housing parts and is connected fixed in terms ofrotation to a shaft which is driven by the electric motor, and having asupport arrangement for the shaft in a housing part, characterized inthat a plastic casing (11) of a rotor (10) of the electric motor (1) isfabricated in one piece with a bush (13) which is arranged in thehousing part (5), and in that the housing part (5) has a support shell(14) for the bush (13).
 2. The delivery unit as claimed in claim 1,characterized in that the bush (13) has a coupling (16) for connectionto the impeller wheel (7) so as to be fixed in terms of rotation.
 3. Thedelivery unit as claimed in claim 1 or 2, characterized in that thecoupling (16) of the bush (13) has a lateral flattered portion forconnection to the impeller wheel (7) so as to be fixed in terms ofrotation.
 4. The delivery unit as defined in claim 2, characterized inthat the coupling (16) is designed to generate a positive lock betweenthe bush (13) and the impeller wheel (7).
 5. The delivery unit asdefined in claim 4, characterized in that the bush (13) and the impellerwheel (7) have projections (17) and recesses (18) respectively, whichcorrespond to one another.
 6. The delivery unit as defined in claim 1,characterized in that the bush (13) is arranged on the shaft (8).
 7. Thedelivery unit as defined in claim 1, characterized in that the bush (13)is fabricated in one piece with an internal plastic casing (11), and aplurality of external plastic casings (12), of the rotor (10).